A technique disclosed herein relates to optical elements including surfaces having antireflection structures configured to reduce reflection of incident light.
In recent years, various optical elements including surfaces having antireflection structures for reducing reflection of light have been proposed.
A technique has been proposed in which fine structural units (e.g., fine structures made of linear recessed portions or linear raised portions, or fine structures made of conical or columnar recessed portions or raised portions) as antireflection structures are formed on a surface of an optical member with a pitch smaller than or equal to the wavelength of incident light.
For example, in Japanese Patent Publication No. 2008-276059, an antireflection structure is formed not only on an optical functional surface of a lens but also on a non-optical functional surface of a cut end portion, or the like, and an opaque film is further formed on the antireflection structure of the non-optical functional surface. In this way, reflection at the entire surface of the lens is reduced.